The movement of goods from points of origin or manufacture to points of consumption or sale often involves the use of tractor trucks pulling trailers, or semitrailers as they are sometimes called. These vehicles are heavy and expensive and require considerable servicing and upkeep to keep them on the road for maximum usage. The tractor portion of this combination has a "fifth wheel" attachment consisting of a base wheel or plate horizontally secured above the rear axle of the tractor. The tractor is attached to the trailer by backing the tractor under the forward end of the trailer to engage an upper plate contained therein such that the upper plate is secured to and rests horizontally on the base plate of the fifth wheel. These upper and base plates provide the connection between the tractor and trailer and rotate relative to each other in a horizontal plane to allow the truck to turn relative to the trailer. Obviously, the facing surfaces of the base and upper plates must be adequately lubricated to minimize wear and friction since these surfaces are constantly rotating against each other.
Heretofore, the only means of lubricating these fifth wheel plate surfaces has been to use a grease gun and spread grease on the surface of the base plate prior to connection of the tractor to the trailer. This is messy and time consuming. It requires the driver of the tractor to carry a grease gun. Sometimes different grease formulations are preferred depending upon loads, weather conditions, etc. In that case the driver has to carry more than one grease gun to make sure the proper grease is available and must identify which grease is to be used under the existing conditions. Many times connections and disconnections of tractors from trailers are made in remote locations where grease may not be readily available. Connections are required in all types of weather. During inclement weather, and particularly in the winter when temperatures are low, grease is difficult to apply due to high viscosities. Also, since blizzard conditions often prevail, there is little incentive to climb from a warm tractor cab, identify the grease gun having the correct grease formulation and force grease from the gun onto a base plate. Often it is necessary to make or switch connections rapidly to meet time schedules and the like. In each case, the necessity of greasing the fifth wheel by means of a grease gun is inconvenient and slows the operation. Safety is also a consideration when applying grease from a gun onto a surface or between surfaces of mating plates of a tractor-trailer combination. Sometimes cramped or close quarters are encountered. It may also be necessary to climb onto the back of the tractor to apply the lubricant to the base plate.
Another problem encountered is that the amount of grease to apply is not always easy to determine because connections are often made during night time hours when visibility is diminished. Because greasing the fifth wheel is such a messy and undesirable job it is sometimes ignored by drivers or service personnel resulting ultimately in breakdowns and increased costs for repairs or replacements.
A search of the art relative to prepackaged grease compositions for lubricating fifth wheels or similar sliding surfaces did not show anything which was considered to be relevant.
Masarky, et al., U.S. Pat. No. 3,858,687, shows a strip of prepackaged fluid lubricant containing envelopes having an adhesive coating on one side. The envelopes are adhesively attached to a cable to enable it to be lubricated as it is passed through a conduit. Friction between the cable and conduit cause the envelopes to burst when lubrication is needed.
Robinson, U.S. Pat. No. 326,156, shows a lubricator for journals and bearings consisting of a closed canvas bag containing grease. The action of moving parts against the bag causes the grease to flow through the pores in the canvas.
Moreno, U.S. Pat. No. 3,469,655, illustrates a grease packer for lubricating automobile front wheel bearings consisting of a cup of grease retentive material sized and shaped to fit over a bearing. A strip-off protective cover seals the cup until ready for use. The cover is stripped off and the cup is inverted over the bearing and pressed to force grease into the bearing.
Sager, U.S. Pat. No. 3,601,252, shows a container having a tubular portion of heat sealable material adapted to hold liquid, granular or solid materials, and which is sealed at one end in such a manner that the seal will rupture when a predetermined pressure is applied at the opposite end. However, usage for purposes of lubrication is not mentioned.
Clarevoe, U.S. Pat. No. 2,889,922, and Stol, U.S. Pat. No. 4,519,866, both show encapsulated adhesives which rupture upon the application of pressure to cause facing surfaces to adhere to each other.